Some wild - and some not so wild - ideas from the major auto manufacturers.

The Flextreme uses the same e-Flex drive system as the Chevrolet Volt concept car shown at the Detroit Auto Show last year. This time, however, a small diesel engine is used to provide on-board power generation. As with the Volt, the Flextreme's batteries can also be charged by plugging into an electrical outlet.

The diesel engine provides additional charge only if needed and is never used to drive the car. On a full charge, the Flextreme can drive about 34 miles before the diesel engine starts. The total range on one 7-gallon tank of fuel is 444 miles.

The Flextreme also carries two Segway electric scooters that are charged from docking stations integrated into the car's cargo bay.